the difference between the apps at the top of the power curve and those near the bottom—or the businesses that make it past the five-year mark versus those that can only get to one year—rarely has much to do with the quality of the idea, or the passion of the entrepreneur, or even the size of the market. More often than not, the success of a new business depends on its ability to get attention—specifically, its ability to build buzz and to engineer word of mouth.